Controlling optics contamination at the PolLux STXM

Watts, Benjamin; Pilet, N.; Sarafimov, B.; Witte, Katharina; Raabe, Jörg

doi:10.1088/1748-0221/13/04/c04001

Cited by 13 publications

(10 citation statements)

References 36 publications

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“…ref. [31]), specifically if compared to other X-ray microscopy installations. The chemical composition of fixed skin is not exactly known, so that the conversion into an absolute vertical scale may lead to substantial errors (cf.…”

Section: Resultsmentioning

confidence: 99%

Soft X-ray microscopy for probing of topical tacrolimus delivery via micelles

Yamamoto

Klossek

Fuchs³

et al. 2019

European Journal of Pharmaceutics and Biopharmaceutics

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The penetration of topically applied tacrolimus formulated in micelles into murine skin is reported, measured by X-ray microscopy. Tacrolimus and micelles are probed for the first time by this high spatial resolution technique by element-selective excitation in the C 1s-and O 1s-regimes. This method allows selective detection of the distribution and penetration depth of drugs and carrier molecules into biologic tissues. It is observed that small, but distinct quantities of the drug and micelles, acting as a drug carrier, penetrate the stratum corneum. A comparison is made with the paraffin-based commercial tacrolimus ointment Protopic ® , where local drug concentrations show to be low. A slight increase in local drug concentration in the stratum corneum is observed, if tacrolimus is formulated in micelles, as compared to Protopic ® . This underscores the importance of the drug formulations for effective drug delivery. Time-resolved penetration shows presence of drug in the stratum corneum 100 min after formulation application, with penetration to deeper skin layers at 1000 min. High resolution micrographs give indications for a penetration pathway along the lipid membranes between corneocytes, but also suggest that the compound may penetrate corneocytes.

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Section: Resultsmentioning

confidence: 99%

Soft X-ray microscopy for probing of topical tacrolimus delivery via micelles

Yamamoto

Klossek

Fuchs³

et al. 2019

European Journal of Pharmaceutics and Biopharmaceutics

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“…Ru samples were composed of a 200 nm thick Ru(0001) film deposited on a yttria-stabilized-zirconia film on top of a Si(111) substrate [17]. As-received samples were first cleaned ex situ in a UV/ozone cleaner [18], followed by thermal annealing in HV (10 −8 mbar) to 700 • C. The samples were not ion sputter cleaned as this damaged the crystallinity and was not required to remove contaminants. More information about sputtering damage is provided in the supporting information (SI) section S1.…”

Section: Methodsmentioning

confidence: 99%

Thermal oxidation of Ru(0001) to RuO₂(110) studied with ambient pressure x-ray photoelectron spectroscopy

Diulus

Tobler

Osterwalder

et al. 2021

J. Phys. D: Appl. Phys.

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The thermal oxidation of Ru(0001) has been extensively studied in the surface science community to determine the oxidation pathway towards ruthenium dioxide (RuO 2 (110)), improving the knowledge of Ru(0001) surface chemistry. Using time-lapsed ambient-pressure x-ray photoelectron spectroscopy (APXPS), we investigate the thermal oxidation of single-crystalline Ru(0001) films toward rutile RuO 2 (110) in situ. APXPS spectra were continuously collected while the Ru(0001) films were exposed to a fixed O 2 partial pressure of 10 −2 mbar and the sample temperature was increased stepwise from room temperature to 400 • C. We initially observe the removal of adventitious carbon and subsequent formation of a chemisorbed oxygen overlayer at 250 • C. Further annealing to 300 • C leads to an increase in thickness of the oxide layer and a shift in the Ru-O component of the Ru 3d spectra, indicating the presence of a metastable O-Ru-O trilayer structure. A rapid formation of the RuO 2 rutile phase with an approximate thickness of at least 2.6 nm is formed about four minutes after stabilizing the temperature at 350 • C and subsequent annealing to 400 • C, signaled by a distinct binding energy shift in both the Ru 3d and O 1s spectra, as well as quantitative analysis of XPS intensities. This observed autocatalytic oxidation process agrees well with previous theoretical models and experimental studies, and the data provide the unambiguous spectral identification of one proposed metastable precursor required for full oxidation to rutile RuO 2 (110). Further ex situ characterization of the grown oxide with x-ray photoelectron diffraction confirms the presence of three rotated domains of rutile RuO 2 (110) and reveals their orientation relative to the substrate lattice.

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“…The bright horizontal band observed both before and after installing the shield corresponds to the path of the X-ray beam, which is made visible due to emission by a small pressure of oxygen in the chamber for in situ removal of carbon contamination on the mirror (e.g. Toyoshima et al, 2012;Watts et al, 2018). Strong light is also observed around the mirror surface before installing the shield, which may be due to the reflection of visible light from the viewport.…”

Section: First-mirror Chambermentioning

confidence: 96%

Photoelectron shield for the first mirror of a soft X-ray beamline

Wakabayashi

Tanaka

Toyoshima

et al. 2021

J Synchrotron Radiat

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At a soft X-ray beamline with an undulator source, significant heat generation at the first-mirror chamber and light emission at the viewport were found, which can be explained by photoelectrons from the mirror. The chamber temperature increases up to approximately 50°C over a period of several hours. A photoelectron shield consisting of thin copper plates not only prevents the heat generation and light emission but also improves the pressure of the vacuum chamber, if a voltage of a few tens of V is applied to the shield. The total electron yield of the shield reached as much as 58 mA under high heat-load conditions, indicating the emission of numerous photoelectrons from the first mirror. Heat-balance analyses suggest that approximately 30% or more of the heat load on the first mirror is transferred to the surroundings.

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Controlling optics contamination at the PolLux STXM

Cited by 13 publications

References 36 publications

Soft X-ray microscopy for probing of topical tacrolimus delivery via micelles

Soft X-ray microscopy for probing of topical tacrolimus delivery via micelles

Thermal oxidation of Ru(0001) to RuO₂(110) studied with ambient pressure x-ray photoelectron spectroscopy

Photoelectron shield for the first mirror of a soft X-ray beamline

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Controlling optics contamination at the PolLux STXM

Cited by 13 publications

References 36 publications

Soft X-ray microscopy for probing of topical tacrolimus delivery via micelles

Soft X-ray microscopy for probing of topical tacrolimus delivery via micelles

Thermal oxidation of Ru(0001) to RuO2(110) studied with ambient pressure x-ray photoelectron spectroscopy

Photoelectron shield for the first mirror of a soft X-ray beamline

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Product

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Thermal oxidation of Ru(0001) to RuO₂(110) studied with ambient pressure x-ray photoelectron spectroscopy